1. Field of the Invention
The invention relates to a process for the preparation of neutral polythiophenes based on 3,4-alkylenedioxythiophenes, in particular 3,4-ethylenedioxythiophene (also 2,3-dihydrothieno[3,4-b][1,4]dioxine), neutral polythiophenes soluble in organic solvents, and their use.
2. Brief Description of the Prior Art
The pertinent class of compounds which consists of the xcfx80-conjugated polymers has been the subject of numerous publications in recent decades. They are also referred to as conductive polymers or as synthetic metals. Owing to the considerable delocalization of the xcfx80-electrons along the main chain, these polymers exhibit interesting (nonlinear) optical properties and are good electrical conductors after oxidation or reduction. Consequently, these compounds can be used in various practical applications, such as, for example, in data storage, optical signal processing, suppression of electromagnetic interference (EMI) and conversion of solar energy, and in rechargeable batteries, light-emitting diodes, field effect transistors, circuit boards, sensors, capacitors and antistatic materials.
Examples of known xcfx80-conjugated polymers are polypyrroles, polythiophenes, polyanilines, polyacetylenes, polyphenylenes and poly(p-phenylene-vinylenes). A particularly important and industrially used polythiophene is poly(ethylene-3,4-dioxythiophene), which has very high conductivities in its doped form, cf. for example EP 339 340 A2. The preparation of the doped poly(ethylene-3,4-dioxythiophene) is effected according to EP 339 340 A2 by oxidative polymerization of 3,4-ethylenedioxythiophene. The processibility of the product is achieved, for example, by the use of poly(styrenesulphonate) as a counter ion in aqueous dispersion.
In comparison, products which are likewise highly conductive but unprocessible are obtained, for example in the form of coatings, by electropolymerization (e.g. xe2x80x9cQ. Pei, G. Zuccarello, M. Ahlskog and O. Inganxc3xa4s, Polymer 35 (1994), pages 1347-1351xe2x80x9d).
According to xe2x80x9cT. Yamamoto and M. Abla, Synth. Met. 100 (1999), pages 237-239xe2x80x9d, it is not possible completely to eliminate the doping of a doped poly(ethylene-3,4-dioxythiophene) prepared according to EP 339 340 A2 or prepared in a similar manner by oxidative polymerization, and thus to prepare a neutralxe2x80x94and thereby undopedxe2x80x94poly(ethylene-3,4-dioxythiophene). Doping according to Yamamoto means oxidation and thereby generating positive charged poly(ethylene-3,4-dioxythiophene).
According to xe2x80x9cS. Garreau, G. Louarn, J. P. Buisson, G. Froyer, S. Lefrant, Macromolecules 32, (1999) pages 6807-6812xe2x80x9d, it is just as impossible completely to dedope the electrochemically produced doped poly(ethylene-3,4-dioxythiophene) by an electrochemical method.
Neutral poly(ethylene-3,4-dioxythiophene) has therefore always been prepared to date by so-called reductive, organometallic synthesis from 2,5-dihalogeno-ethylene-3,4-dioxythiophene. xe2x80x9cSynth. Met. 100 (1999), pages 237-239xe2x80x9d and xe2x80x9cPolymer 43 (2002), pages 711-719xe2x80x9d disclose a process for the preparation of neutral, undoped poly(ethylene-3,4-dioxythiophene) by dehalogenating polycondensation of 2,5-dichloro-ethylene-3,4-dioxythiophene in the presence of bis(1,5-cyclooctadiene)nickel(0). However, only an insoluble poly(ethylene-3,4-dioxythiophene) can be obtained by this process.
xe2x80x9cJ. Mater. Chem. 11, (2001) pages 1378-1382xe2x80x9d describes the preparation of soluble, neutral, undoped poly(ethylene-3,4-dioxythiophene) by polycondensation of 2,5-dibromo-ethylene-3,4-dioxythiophene in the presence of Ni(0) prepared in situ. As a result of the preparation, however, a material synthesized in this manner contains organically bound bromine. Owing to the danger of HBr or bromide elimination, such chemically noninert terminal groups on the polymer are undesired in applications in the electronics industry. Moreover, this product has also been described as being only partly soluble in dimethylacetamide.
In addition, the processes, described in xe2x80x9cSynth. Met. 100 (1999), pages 237-239xe2x80x9d, xe2x80x9cJ. Mater. Chem. 11, (2001) pages 1378-1382xe2x80x9d and xe2x80x9cSynth. Met. 119 (2001), pages 381-382xe2x80x9d are not economical compared with simple oxidative polymerization processes, owing to the additional synthesis step via the 2,5-dihalogenoethylene-3,4-dioxythiophene and the use of expensive, sensitive organometallic reagents.
One possibility for obtaining soluble, neutral and undoped derivatives of poly(ethylene-3,4-dioxythiophene) which are soluble in organic solvents by oxidative polymerization consists in substitution of the ethylene unit by alkyl or alkoxymethyl groups having 10 or more C atoms. Correspondingly substituted poly(ethylene-3,4-dioxythiophenes) are described in xe2x80x9cAdv. Mater. 12, (2000) pages 481-494xe2x80x9d, xe2x80x9cPolym. Mater. Sci. Eng. 72, (1995) page 319 et seq.xe2x80x9d, xe2x80x9cMacromolecules 30, (1997) page 2582 et seq.xe2x80x9d, xe2x80x9cMacromolecules 29, (1996) page 7629 et seq.xe2x80x9d, xe2x80x9cChem. Mater. 10, (1998) page 896 et seq.xe2x80x9d, xe2x80x9cSynth. Met. 102, (1999) page 967 et seq.xe2x80x9d, xe2x80x9cJ. Chim. Phys. 95, (1998) page 1258 et seq.xe2x80x9d, xe2x80x9cSynth. Met. 101, (1999) pages 7-8xe2x80x9d and xe2x80x9cChem. Mater. 8, (1996) pages 769-776xe2x80x9d. Common to all articles mentioned is that neutral and therefore undoped derivatives of poly(ethylene-3,4-dioxythiophene) which are soluble in organic solvents are obtained only when the substituents on the ethylene unit of the 3,4-ethylenedioxythiophene have at least 10 carbon atoms.
xe2x80x9cPolymer 42 (2001), pages 7229-7232xe2x80x9d describes a neutral, undoped polymer of 2-n-hexyl-2,3-dihydrothieno[3,4-b][1,4]dioxine units. However, the preparation is effected via the complicated synthesis method described in xe2x80x9cSynth. Met. 100 (1999), pages 237-239xe2x80x9d, by polycondensation of the 2,5-dichlorothiophene derivative in the presence of Ni(0); on the other hand, the oxidative synthesis was designated as being unsuitable as the preparation method.
EP 686 662 A2 mentions a neutral poly(ethylene-3,4-dioxythiophene). However, the polymerization is carried out according to EP 339 340 A2 and EP 440 957 A2. However, doped, nonneutral poly(ethylene-3,4-dioxythiophene) is prepared in this manner. A comparison of the properties of poly(ethylene-3,4-dioxythiophene) prepared according to EP 686 662 A2 with the properties of neutral poly(ethylene-3,4-dioxythiophene) which is without a doubt undoped and which is prepared according to xe2x80x9cSynth. Met. 100 (1999), pages 237-239xe2x80x9d or xe2x80x9cJ. Mater. Chem. 11, (2001) pages 1378-1382xe2x80x9d also shows that EP 686 662 A2 by no means describes neutral poly(ethylene-3,4-dioxythiophene).
No process is known to date for the preparation of neutral and therefore undoped poly(ethylene-3,4-dioxythiophene) or derivatives which carry a C1-C9-alkyl substituent on the ethylene unit by an oxidative method.
The preparation of a completely halogen-free poly(ethylene-3,4-dioxythiophene) which is also soluble in organic solvents has been just as impossible to date.
It is an object of the present invention to prepare neutral poly(ethylene-3,4-dioxythiophene) which is soluble in organic solvents and free of organically bound halogen, or poly(ethylene-3,4-dioxythiophene) derivatives substituted by short chains and unknown to date in neutral form and in a form dissolved in organic solvents, by an economical and simple method.
The invention thus relates to a process for the preparation of neutral compounds of the general formula (I), 
in which
R1 and R2, independently of one another, each represent H or C1 to C9-alkyl, it also being possible for R2 to represent CH2xe2x80x94Oxe2x80x94R3, with R3=H or C1 to C9-alkyl, cycloalkyl or aralkyl, when R1 represents H, and
n represents an integer from 2 to 200,
by reaction of monomers of the general formula (II), 
in which
R1 and R2 have the abovementioned meanings,
with an oxidizing agent, the reaction being carried out in an organic solvent and the oxidizing agent being used in an amount of 50 to 99.9% of the stoichiometrically required amount.
The invention is described more fully hereunder with particular reference to its preferred embodiments, as follows. R1 and R2, independently of one another, are each preferably H or C1 to C5-alkyl, it also being possible for R2 to denote CH2xe2x80x94Oxe2x80x94R3, where R3=H or C1 to C5-alkyl, when R1 represents H. R1 and R2, independently of one another, particularly preferably each represent H or C1 to C2-alkyl, it also being possible for R2 to denote CH2xe2x80x94Oxe2x80x94R3, where R3=H or C1 to C4-alkyl, when R1 represents H. R1 and R2 particularly preferably represent H.
The neutral compounds according to the invention are also called neutral, undoped compounds.
The reaction according to the invention is carried out in an organic solvent. An organic aprotic solvent is preferably used, in particular a halogenated hydrocarbon is used. A halogenated hydrocarbon from the group consisting of chloroform, methylene chloride and chlorobenzene is very particularly preferably used.
The oxidizing agents used may be the oxidizing agents customary for the oxidative polymerization of thiophenes and known to a person skilled in the art, it being possible for certain restrictions to apply depending on the chosen reaction conditions and in particular on the chosen organic solvent. For given reaction conditions, suitable oxidizing agents can readily be determined by means of simple preliminary experiments.
A preferably used oxidizing agent is an iron(III) compound, particularly preferably used oxidizing agent is iron(III) chloride or iron(III) tosylate, very particularly preferably used oxidizing agent is iron(III) chloride.
An important feature of the process according to the invention is the fact that the oxidizing agent is typically used in less than stoichiometric amounts, i.e. in an amount of 50 to 99.9% of the stoichiometrically required amount. For the polymerization of a thiophene monomer, theoretically 2 equivalents of the oxidizing agent are required per mole of the monomer. It is essential for the invention that not more than 99.9%, preferably not more than 99%, and at least 50%, preferably at least 75%, of the stoichiometrically required amount of oxidizing agent are used. Particularly preferably, 80 to 96% of the stoichiometrically required amount are used.
Accordingly, when carrying out the process according to the invention, it should be ensured that the reactants are always present in the reaction mixture in amounts such that an excess of oxidizing agent of more than 1.998:1, relative to the monomer present in the reaction mixture, is never present. Thus, preferred reaction procedures are those in which the thiophene monomer is initially introduced and the oxidizing agent is metered in in portions or continuously so that more than 1.998 mol, at the most, of the oxidizing agent cannot be present at any time per mole of monomer in addition to the monomer. As a rule, however, the reaction is carried out in such a way that the molar ratio of oxidizing agent to monomer is substantially less than 1.998:1 during the entire reaction time.
The process according to the invention can be carried out at room temperature. However, it may also be expedient to work at lower temperatures, e.g. 0xc2x0 C., or at higher temperatures, e.g. at the reflux temperature of chloroform (about 60xc2x0 C.) or an even higher temperature, which is possible, for example, in chlorobenzene. 0 to 100xc2x0 C. is preferably employed, particularly preferably employed is 15 to 65xc2x0 C.
In the process, particularly if iron(III) tosylate or iron(III) chloride is used as the oxidizing agent, the yield of desired neutral polythiophene can be increased if a base is added in at least equimolar amounts during the reaction for neutralizing acids (p-toluenesulphonic acid or HCl) formed from the oxidizing agent. Such a procedure is therefore preferred. Suitable bases are, for example, ammonia, amines or basic metal oxides. However, alkali metal or alkaline earth metal carbonates, e.g. sodium carbonate, potassium carbonate or calcium carbonate, are preferably used.
The reaction can be carried out under air or under an inert gas, e.g. nitrogen or argon. Carrying out the reaction under an inert gas is advantageous for increasing the yields, but is not essential.
Monomers used in the process according to the invention are ethylene-3,4-dioxythiophenes of the formula (II) which are optionally substituted on the ethylene unit. According to IUPAC, such compounds are designated as 2,3-dihydrothieno[3,4-b][1,4]dioxines.
Suitable monomers are listed below by way of example using the IUPAC nomenclature.
The following may be mentioned by way of example as suitable monomers of the formula (II), in which R1 is H and R2 is H or C1 to C9-alkyl:
2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-methyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-ethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-propyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-butyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-pentyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-hexyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-heptyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-octyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(2-ethyl-hexyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-nonyl-2,3-dihydrothieno[3,4-b][1,4]dioxine.
Preferred examples from this group are 2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-methyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-ethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-propyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-butyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-n-pentyl-2,3-dihydrothieno[3,4-b][1,4]dioxine.
Particularly preferred examples from this group are 2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-methyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-ethyl-2,3-dihydrothieno[3,4-b][1,4]dioxide.
2,3-Dihydrothieno[3,4-b][1,4]dioxine is very particularly preferred.
The following may be mentioned by way of example as suitable monomers of the formula (II), in which R1 and R2, independently of one another, represent C1 to C9-alkyl:
2,3-dimethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2,3-diethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2,3-di-n-propyl-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2,3-di-n-butyl-2,3-dihydrothieno[3,4-b][1,4]dioxine.
The following may be mentioned by way of example as suitable monomers of the formula (II), in which R1 represents H and R2 represents xe2x80x94CH2xe2x80x94Oxe2x80x94R3 with R3=H, C1-C9-alkyl, C1-C9-cycloalkyl or C1-C9-aralkyl:
2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethanol, 2-(methoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(ethoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-propoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-butoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-pentyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-hexyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-heptyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-octyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(2-ethylhexyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-nonyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(cyclopentyloxymethyl )-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(cyclohexyloxymethyl )-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(benzyloxymethyl)-2,3-dihydrothieno[3,4-b]-[1,4]dioxine.
Preferred monomers from this group are: 2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethanol, 2-(methoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(ethoxymethyl )-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-propoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-butoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-pentyloxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine.
Particularly preferred monomers from this group are: 2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethanol, 2-(methoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(ethoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-propoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine, 2-(n-butoxymethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine.
The concentration of the monomers in the organic solvent can be chosen within a wide range. The monomer is preferably used in a concentration of 0.2 to 5% by weight.
By means of the process according to the invention, it is possible to prepare neutral polymers of the formula I, in which n represents an integer from 2 to 200, preferably 2 to 50, particularly preferably 2 to 30.
It is also possible to obtain neutral copolymers of the formulae (III) or (III a), 
in which
R1 and R2, independently of one another, each represent H or C1 to C9-alkyl, it also being possible for R2 to be CH2xe2x80x94Oxe2x80x94R3, with R3=H or C to C9-alkyl, cycloalkyl or aralkyl, when R1 represents H,
R4 represents a linear or branched alkyl group having 1 to 18 C atoms, an optionally C1- to C6-alkyl-substituted cycloalkyl group having a total of 5 to 12 C atoms, an optionally substituted aryl group having 6 to 10 C atoms or a linear or branched C1-C18-alkoxy group,
R5 represents a linear or branched alkyl group having 1 to 18 C atoms, an optionally C1- to C6-alkyl-substituted cycloalkyl group having a total of 5 to 12 C atoms, an optionally substituted aryl group having 6 to 10 C atoms or an aralkyl group having 7 to 12 C atoms, and
n and m, independently of one another, represent an integer from 1 to 200.
For this purpose, the procedure as described above is adopted, a mixture of a compound of the formula (II) and a compound of the formula (IV) 
in which
R4 represents a linear or branched alkyl group having 1 to 18 C atoms, an optionally C1- to C6-alkyl-substituted cycloalkyl group having a total of 5 to 12 C atoms, an optionally substituted aryl group having 6 to 10 C atoms or a linear or branched C1-C18-alkoxy group, and
R5 represents a linear or branched alkyl group having 1 to 18 C atoms, an optionally C1- to C6-alkyl-substituted cycloalkyl group having a total of 5 to 12 C atoms, an optionally substituted aryl group having 6 to 10 C atoms or an aralkyl group having 7 to 12 C atoms,
being used as monomer.
Corresponding thiophene polymers or copolymers have not been obtainable to date by an oxidative method in a neutral, undoped form soluble in organic solvents. The thiophene polymers and copolymers are distinguished in particular by the fact that they are soluble in organic solvents and free of organically bound halogen.
The invention also relates to neutral compounds of the general formula (I), 
in which
R1 and R2, independently of one another, each represent H or C1 to C5-alkyl, it also being possible for R2 to be CH2xe2x80x94Oxe2x80x94R3, with R3=H or C1 to C9-alkyl, cycloalkyl or aralkyl, when R1 represents H, and
n represents an integer from 2 to 200,
these being soluble in organic solvents and being free of organically bound halogen.
Compounds which can be dissolved in an amount of at least 1% by weight, preferably at least 5% by weight, particularly preferably at least 10% by weight, in at least one organic solvent are designated as being soluble in the context of this application. Organic solvents are understood as meaning, for example, halogenated aliphatic hydrocarbons, aromatic hydrocarbons, halogenated aromatic hydrocarbons, dialkyl ethers, cyclic ethers and dipolar aprotic organic solvents.
The compounds according to the invention preferably dissolve in an amount of at least 1% by weight in an organic solvent selected from the group: chloroform, methylene chloride and tetrahydrofuran. They preferably dissolve in an amount of at least 5% by weight, particularly preferably in an amount of at least 10% by weight.
Compounds understood as being free of halogen are those which contain less than 1000 ppm, preferably less than 500 ppm, particularly preferably less than 100 ppm, of halogen.
Neutral compounds of the general formula I, in which R1 and R2, independently of one another, represent H or C1 to C2-alkyl, or R1 denotes H and R2 denotes CH2xe2x80x94Oxe2x80x94R3 with R3=H or C, to C4-alkyl, are preferred.
Compounds of the formula I in which R1 and R2 represent H are particularly preferred.
The invention furthermore relates to neutral copolymers of the formulae (III) or (III a), 
in which
R1 and R2, independently of one another, each represent H or C1 to C9-alkyl, it also being possible for R2 to be CH2xe2x80x94Oxe2x80x94R3, with R3=H or C1 to C9-alkyl, cycloalkyl or aralkyl, when R1 represents H,
R4 represents a linear or branched alkyl group having 1 to 18 C atoms, an optionally C1- to C6-alkyl-substituted cycloalkyl group having a total of 5 to 12 C atoms, an optionally substituted aryl group having 6 to 10 C atoms or a linear or branched C1-C18-alkoxy group,
R5 represents a linear or branched alkyl group having 1 to 18 C atoms, an optionally C1- to C6-alkyl-substituted cycloalkyl group having a total of 5 to 12 C atoms, an optionally substituted aryl group having 6 to 10 C atoms or an aralkyl group having 7 to 12 C atoms, and
n and m, independently of one another, represent an integer from 1 to 200,
which copolymers are obtainable by the process according to the invention and are soluble in organic solvents and free of organically bound halogen.
The structures (III) and (III a) may be present side by side in any desired ratio and also in the same polymer molecule; furthermore, the sequences of the monomers and the polymer structure are arbitrary, but preferably random. However, blocks of different length may also occur in the molecules.
In the copolymers of the formulae (III) and (III a) according to the invention, R4 preferably denotes methyl, phenyl or OR5 and R5 preferably denotes C1- to C18-alkyl, particularly preferably R4xe2x95x90OR5=methoxy, ethoxy, n-propoxy, n-butoxy, n-hexyloxy, 2-ethylhexyloxy, n-octyloxy, n-decyloxy, n-dodecyloxy or n-tetradecyloxy.
R1 and R2, independently of one another, preferably represent H or C1 to C2-alkyl, or R1 represents H and R2 represents CH2xe2x80x94Oxe2x80x94R3, with R3=H, C1 to C4-alkyl, and R1 and R2 particularly preferably represent H.
The compounds of the formula (I) according to the invention and the copolymers of the formulae (III) and (IIIa) according to the invention are preferably prepared by the process according to the invention.
The polythiophenes prepared by the process according to the invention or polythiophenes according to the invention are intense red-brown, red or violet-brown solids which are soluble in organic solvents, such as methylene chloride, chloroform or tetrahydrofuran, and whose solutions fluoresce. For applications, for example in the electronics industry, they are therefore readily processible from organic solution. Doped, cationic polythiophenes or polythiophene layers can be prepared readily, i.e. also using mild oxidizing agents, from such solutions in the presence of a counter ion.
The neutral compounds or copolymers prepared according to the invention or said compounds or copolymers according to the invention can therefore be used for the preparation of cationic and therefore doped polythiophenes, the neutral compounds or copolymers being oxidized in the presence of a protic acid.
The neutral compounds or copolymers prepared according to the invention or said compounds or copolymers according to the invention can also be used for the production of layers of cationic polythiophenes by applying the neutral compounds or copolymers to a substrate and oxidizing them by atmospheric oxygen in the presence of an organic sulphonic acid, for example from the group consisting of p-toluenesulphonic acid, p-n-dodecylbenzenesulphonic acid and poly(styrenesulphonic acid). The application to the substrate can be effected in the form of a solid or from solution before or after the oxidation. Suitable methods for applying solids or solutions to substrates are sufficiently well known. Application from solution by means of knife-coating, spin-coating or inkjet methods may be mentioned here by way of example.
The neutral compounds or copolymers prepared according to the invention or said compounds or copolymers according to the invention can moreover be used in neutral form or in subsequently doped and therefore cationic form for the production of electrical or electronic components, for example for the production of fluorescent elements, photocells or organic transistors, for the treatment of plastics films for the packaging of electronic components and for clean-room packaging, for the antistatic treatment of cathode ray tubes, for the antistatic treatment of photographic films, as transparent heating, as transparent electrodes, as circuit boards or for electrically colourable window panes.